1. Field of the Invention
The present invention relates to cooking oil filtering and recovery systems.
2. Description of the Prior Art
Restaurants consume large quantities of cooking oil in food preparation. In particular, most restaurants, especially those in the so-called "fast food" industry, employ a technique known as "deep-fat frying" which requires a large amount of cooking oil for each cooking operation.
After the cooking oil in a deep-fat fryer has been used a limited number of times, the oil tends to become dirty and rancid, causing undesirable odors and unacceptable food product. This is due in part to the oxidation and polymerization of the oil, caused by cooking at elevated temperatures for extended periods of time. Further, certain fatty acids such as palmitic, oleic, amino, and stearic acids, are imparted into solution with the cooking oil from the foods cooked. The cooking oil more readily becomes rancid when the acidity of the oil rises to a certain level. Another difficulty is experienced with hydrogenated fats when used in cooking, in that such fats tend to polymerize and decompose once melted and then allowed to reharden.
Several systems have been developed for filtering cooking oil and extending the period for which the oil may be used. See, for example, U.S. Pat. No. 3,648,595. Many of these systems simply filter the solid materials in the oil but do not remove most of the odor-causing components which are in the solution with the cooking oil.